There were immediate queries about how he managed to get past security, especially considering that Abdulmutallab was included on the Terrorist Identities Datamart Environment database, a list of 550,000 individuals who are known or suspected terrorists.

Despite this, Abdulmutallab was not subjected to secondary screening procedures.

In addition to being on a national watchlist, other warning signs could have identified him as a suspicious individual. For example, he purchased an expensive airline ticket using cash in a country different to that of his port of embarkation or his intended destination; and, he was traveling without any checked luggage for a two-week trip over the Christmas period, according to an article by Reuters.

Secretary of Homeland Security, Janet Napolitano, admitted in a Dec. 28 NBC interview that security measures “did not work,” despite having said earlier in the week that the system had worked properly. President Barack Obama on Dec. 28 ordered a review of the nation's watchlist system and its air safety regulations.

Leeann Pierce Carolla, president of Pierce, Pugliese, & Carolla Air Analytics who was also a manager for United Airlines for 13 years, said that it is airlines who need to step up security measures and take greater responsibility for securing its passengers. “That’s where everything breaks down, because airlines don’t have anything in place that serves as a separate and additional layer of security to catch these people,” she said.

While she admits the TSA needs to vastly improve its training and procedures to ensure that passengers and luggage are properly and thoroughly screened, blame for these incidents cannot fall solely on the agency. “You cannot look at TSA and say this is all TSA’s fault,” she said. “I’ve worked in every aspect of United’s operations and the thing I’ve always said, and will always say, is that failings always occur prior to the security checkpoint.”

One of the most significant changes to airline procedures that had a negative impact on security was the automation of the ticketing system and thus the elimination of direct contact with passengers. “We’ve gone from personal check-in policies to using credit cards to check in and that’s appalling to me,” she said. “When we don’t talk to persons directly, then they have no problem coming up last minute and buying a ticket and there’s nobody looking. If they don’t have luggage, they can go straight through to the aircraft. There’s no fail safe and it becomes all the TSA’s responsibility.”

Depending solely on the TSA to determine whether or not passengers should be allowed to travel is too burdensome for one agency to handle, she said. Instead, Carolla said, an airline needs to spend the money to properly train and educate its agents, from customer service representatives to flight attendants, about how to properly evaluate and detect behavioral indiscretions of travelers.

“Airlines have never embraced individual security measures in their corporate structures and they feel they don’t have the money to do such things and don’t want to do it to become their own defenders,” she said. However, depending solely on the TSA to provide security services and protect aircraft obviously has its failings.

Another one of those failings said Nick Naclerio, an aviation security consultant with NJ Naclerio & Associates, is a serious gap in security measures aboard aircrafts. “Once the plane is loaded with passengers who have been screened and searched, we need to look at their behavior in flight,” he said.

Behavior profiling aboard planes is critical, he said, but difficult to implement with the current systems. “Pilots are in the cockpit behind double doors, so really the front lines are flight attendants,” he said. “They tend to be the lowest paid and have enough to do, but as a result, no one has any idea what passengers are doing during flights.”

For example, there is no system to identify if a passenger has spent an inordinate amount of time in a lavatory, as was the case during a second scare aboard the same Amsterdam to Detroit flight only two days after Abdulmutallab’s botched attempt.

To provide the airline crew aboard the plane as well as officials on the ground with better intelligence regarding suspicious behavior aboard flights, Naclerio said he has developed an Airline Passenger Management System, which monitors the real-time activity of passengers.

The system uses a wireless network that provides the physical status of each passenger so that the crew can monitor, manage, control and restrain passengers as required during flight, said Naclerio. The crew would use handheld devices and flat-screen monitors to continually report on the status of each passenger. The system would also integrate background information about each passenger and report on the status of seat belts, passenger location and the movement by passengers aboard the plane.

“This system would provide an extra layer of protection,” he said, ensuring the airline crew, as well as the TSA, had a more comprehensive understanding of the activity aboard flights.

And while Carolla agrees that such a system could be beneficial for aircrew, she expressed concern that an overabundance of information might overwhelm them, at least initially. However, she did say that additional information about passengers could improve crewmembers’ ability to know what was happening aboard a flight and help maintain the safety of passengers and aircraft.